Telephone system.



PATENTED AUG. 4,' 19o8.- y

W. Vw. DEAN. TELEPHONE SYSTEM APPLICATION FILED DBC. 22.1902.

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UNITED STATES PATENT oFFToE..

WILLIAM W. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO KFLLOGG SWITCIIBOAHDAND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, (TORIORTIOX OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Lettels Patent.

Patented Ang. 4,A 1908.

Application led December 22, 1902. Seal No. 136,095.

To (1Z t/fzom it may concern.'

Be. 1t known that I, WILLLm W. Deax, a

citizen of the Ltnited States, and residing at Chicago, in the county ofCook and State` of Illinois, have invented new and useful Improvementsin Telephone Systems, of which the following is a specification.

My invention relates to telephone systems and particularly to thesupervisory apparatus associated with the multiple switch connections ofthe lines at. the central oflice.

It issometimes desirable to use supervisory signals that are negativeincharacter, that is, such as are visible during conversation and areextinguished to give the disconnect indication. It is moreover desirablewith such signal to employ a pilot relay that is positivo in characterand which becomes lighted when the other signals are rendered inert.

)Iy invention consists in the several features of the line circuit andthe supervisory apparatus hereinafter described A and particularlypointed out in the ppended claims.

In the accompanying drawing forming a part of this specification and inwhich the figure is a diagram of a telephone system embodying myimprovements, the same reference characters are used throughout toindicate like parts.

L and I,2 represent telephone lilies extendingr from their respectivesubstations in two limbs 2 and 3 to the central oflice. At thesub-stations, station A for example` a call bell 1t and condenser 5 arepreferably permanently connected between the line conductors, while thereceiver 6 and transmitter 7 arel in a bridge of the line normally openat the switch-hook S. Any other arrangement or type of common batterysets may be employed. Atthe central otlice a plurality of jacks such asJ and J2 are provided for each of the lines, the line conductor 3 beingextended through series contacts 9 in each of the jacks to ground whilethe tip conductor extends through the series contacts 10 thereof andthence by conductor 11 to the line signal S which is joined upon itsother terminal by conductor 12 with the central and common battery B.The line signal shown is of the mechanical type preterably such as havea grating 13 in front of the target 1t of the signal. The target isprovided with colored strips, preferably white, normally behind the barsof the grating 13 but which when the signal is actuated l are moved intoline with the openings in the grating so as to be readily seen. \\'itl1this arrangement a slight movement of the target serves to give afulland readily visible signal.

The cord circuit is provided with an answering plug I) and a callingplug P adapted to register with the contact surfaces of the jacks andwhen inserted to lift the tip springs thereof so as to open the contacts9 and 10 and thereby cut-oill the ground connection and the signal S.The tip contacts of the plugs are joined by strands t and i2 connectedtogether inductivcly through the plates of the condenser' c, while thesleeve contacts of the plugs are inductively joined by the strands s ands2 and the condenser cf. A supervisory signal Sl of the mechanical typejust described has two balancing windings 15 and 1G connected in theconductors 1T and 1S leading respectively from the strands t and s tothe grounded and live poles of thehattcry B. similar supervisory signalfor the calling end of the cord circuit 1s connected by means ofconductor 19 between the strand t" and the grounded pole of the batteryB. A relay r has winding 20 connected in a conductor 2 between the livepole of the battery B and the sleeve strand s? of the cord circuit. lpilot lamp or similar signal S* has its circuit completed from thebattery B, by conductor 22 through the pilot relay r2, which conductorleads to the spring 23 of said relay r, the. forward contact of which istact or armature 25 of the signal S", which is connected by conductor 2Gwith the grounded conductor 17. A third contact 2T is )rovided upon thecalling plug I2 and whiclh is adapted to be electrically connected withthe ordinary sleeve contact of said plug by means of the test ring orsleeve contact of the jack of the line. A conductor 2S leads from saidcontact 2T through a retardation coil '29 which is preferably locatedupon the core of said relay r. The tip strand of the cord circuity isopen atv the front contact of spring 30 of `relay r and the forwardportion of said strand is connected through said spring and its backcontactv with a conductor 31 leading to the high impedance and highresistance test relay r3, the opposite pole of which is grounded. Theoperators transmitter 32 is connected in a conductor 33 leading from thelive pole of battcrv B through a retardation coil 34 to ground. Theprimary windjoined by conductor 24. with the back coning of theoperators induction coil 35 and the condenser c3 are connected in ashunt of the transmitter 32. The operators receiver, the secondary ofher induction coil 35 and a condenser are adapted to be bridged acrossthe cord circuit by the springs 36 of any suitable listening key. Thegenerator 3T having one pole grounded is arranged to be connected withthe tip side of the cord circuit by the springs 38 of a suitable ringingkey while at the same time the sleeve cord is grounded. This connectionof the generator serves to operate the call bell located at the stationC while a depression of the springs 3D of the ringing key connects thcsaid generator similarly with the other side ot' the cord circuit toring the bell at the station D. Owing to the series contacts of thcjacks, no cut-oli relays are required for the lines.

In connecting subscribers for conversation the line signal S is actuatedin the usual way by the removal of the receiver at the substation forconversation. Seeing tl.e line signal the operator connects her cordcircuit with the line, thereby cutting oli the line signal andthe\ground coniiect-ion and causing the opera-tion of the su ervisorysignal S through thcniediuin of tiie current from the battery B which isnow ilowing over the calling line. Thejwanted line is tested in theusual way. If idle the test rings are connected to ground through theseries contacts 9 of the jacks, but if isysuch ground is cut-olf andthey are conne vted with the live pole of the battery, whereby theapplication of the tip of the testing plug permits a flow of currentthrough the test rela-y 11.3 thus energizing the saine and causing it tocomplete a path for current through the primary windin 1r of theoperators induction coil toA cause a cilick in the operators receiver.

Finding the line idle the plug is inserted and the ringing key operated.As before pointed out, either party may be rung by the actuation of theproper springs of the ringing key, the opposite line conductor beinggrounded to provide a low resistance return path for current in case thesubscriber rcspoiidsduring ringing or in case a single subscriber isbeing rung. After ringing and before the subscribers response the relayr is actuated by current over the sleeve strand, through the winding 20,the sleeve contact, test ring of the jack, contact 2T of the plug and:hence by way of conductor 2S and through the 500 ohm winding 29 ofrelay 1 to ground. This relay is therefore operated to close the spring23 upon its forward contact to complete the circuitl at one point of the)ilot relay and to disconnect the test relay by means of the spring 30and complete the tip strand of the cord circuit for talking. Thesupervisory signal S3 has not yet rcs onded since there is no currenttlowing over tlie metallic line. 'hen lthe subscriber re- 4of the relayr furnishes sufIicient retardation to prevent the, passage of the voicecurrents. The battery B furnishes current te both lines for transmissionpurposes and for the operation of the various relays. l.\t the termina-7 tion of the conversation thc return of the receivers to thchooksdeprivcs the signals S and S of operating current and the'signalsare retired. The restoration ofsignaibi coinfil pletes the circuit ofthe pilot rclav i which` 50 is now energized to close the circuitof-t-he pilot lamp'S, in response to which thc operator takes down theconnection and restores all parts to normal condition. It will thus beobserved that av positive pilot signal is ob- 35 tained with the negatic supervisory signals. Of course, the mechanical signals may be replacedby relays and lamps.

Various modilications may be made in my invent-ion and I do nottherefore desire to be limited to thcexact features shown and describedcxcept when such is made necessary by the specific liinit-ations imposedherein. i

I claim. t

1. 'ln a telephone system, the coinbin'ationl 9 with a telephone line,of a cord circuit to establish conversational circuits' therewith, asupervisory signal associated with cach end of thc cor'd circuit andadapted to be rendeied inert at the termination of the couver 100sation, and a supervisory signal common to a plurality of cord circuitsdisplayed when the calling subscriber hangs up his receiver and againeflaced when the calling plug is removed from its connection with thecalled los line, substantially as described. 2. In a telephone system,the combination with a telephone line, of a central source of current, apilot signal for the cord circuit, a

cord circuit to establish conve `sational circuit-s therewith, a relayconnected between the said source and one side of the cord circuit, saidrclay serving to control at one point the circuit of the pilot signal,and

means operated when the subscriber replaces his receiver for closingsaid circuit at ans other ioint, substantially as described. 3. n atelephone system, the combination with a telephone line, of a cordcircuit to a central battery connected between the strands of the cordcircuit a supervisory signal connected between said battery and one ofsaid strands, a relay connected between establish convcisationalcircuits therewith,

said battery and the other of said strands,

said relay servingr to control the current path of said signal over itsstrand, substantially as described 4. Ina telephone systenr` thecombination with a telephone line, of a cord circuit to es-"lg Liri-2sagmal control,

CIL

Sarina jack caben.

signal connected with the answering end of the cord circuit andresponsive to current over the line, said signal being visible duringconversation, a relay actuated over the .calling end of the cordcircuit, and a pilot signal havingr its circuit controlled by said relayand said supervisory signal and adapted to be actuated when said signalis rendered invisible, substantially as described.

5. ln a telephonesystem, the combination g with a telephone line, of acord circuit adapted to be connected therewith for conversationalpurposes,

a supervisory signal associ- 1 l l l l ated with one end of said cordcircuit and 2 adapted to be actuated over the telephone line, a relayassociated with the other end of said cord circuit and adapted to beactuated by current in a local circuit, a pilot signal adapted to bedisplayed when said supervisory signal is in its normal condition andwhen said relay is in its actuated condition, substantiallyvv asdescribed.

(i. ln a telephone system, the combination with a pair of telephonelines, of a cord circuit adapted to connect said lines together forconversation, supervisory signals for said cord circuit, one under thecontrol of each of the subscribers connected for conversation, a relayassociated with the cord circuit and adapted tobe actuated during theconnection of the calling end of the cord circuit with the calledsubscribei"s line, a pilot supervisory signal associated with the cordcir cuit and having its circuit normally open at contacts of said relayand normallyclosed at contacts of said supervisory signal, whereby saidpilot signal is displayed only when said supervisory signal is inert andsaid relay is actuated, substantially as described.

7. In a telephone system, the combination with a `plir of telephonelines having jacks at the centralolliee, of a cord circuit adapted toconnect said lines together for conversation, a callingfplug for saidCord circuit a pair f supervisory signals associated with the coldcircuit, on" ol said signals being controll yd over the callingsubscribei"s line and the other over the` answering subscribe1"s line,a. pilot signal associated pervisory signhls `and adapted to bedisplayed only when` said signal is inert, and means controlled throughcontacts of the plug and jack to prevent the display of said )lot signalwhen the connection is severed between the calling end of the cordcircuit and the called telephone line, substantially as described.

S. In a tele )hone system, the combination with a pair olitelephonclines, of a cord circuit adapted [or conversation, a pair ofsupervisory sigwith one of said sute connect "said lines togethenaitsmaa nals associated, one with each of said lines during theconnectionof the cord circuit therewith, said signals being adapted tobe positively displayed during conversation and negatively displayedwhen the conversation has terminated, and a pilot signal associated withthe cord circuit and adapted to bc negatively displayed duringconversation' and iositively displayed when the conversation iasterminated, and means actuated by the removal of ther calling plugr fromthe jack for again ellacing the pilot signal, substantially asdescribed.

- Signed by me at Chicago, county of Cook, State of Illinois, this 11thday of December WILLIAM W. DEAN. 'itnesscs:

ROBERT LEWIS AMES, GAZELLE BEBER.

